1. Field of the Invention
The present invention relates generally to a call processing method and apparatus in a Voice over Internet Protocol (VoIP) system, and more particularly, to one which can allow a subscriber to receive/originate a call by accessing the subscriber's Internet Protocol (IP) terminal irrespective of the subscriber's location.
2. Description of the Related Art
At present, a variety of services are being provided to subscribers through such networks as wired and wireless Internet networks due to developing network and electronic technologies. A representative service is a VoIP service that supports a telephone call, including images and sounds, over the Internet.
Compared to a conventional Public Switched Telephone Network (PSTN) service, the VoIP service has desirable features such as lower cost and various types of multimedia services.
Previously, the Internet was not regarded as being suitable for real-time information exchange such as a conventional voice call conversation through the PSTN since it is a packet network designed for transmitting and receiving data. That is, it was previously believed that real-time property could not be ensured during the transmission of a voice packet since the voice packet in the packet network can be damaged or delayed by other data packets.
However, when telephone service can be provided over the Internet network, i.e. the packet network, telephone charges may be cheaper than the PSTN service. Furthermore, a multimedia telephone service can be provided by simultaneously exchanging video and data based on the characteristics of the packet network. Accordingly, extensive research has been conducted on technologies that enable telephone service over the Internet, and a plurality of protocols for setting up a call over the Internet, such as H.323, Session Initiation Protocol (SIP) and Media Gateway Control Protocol (MGCP or MEGACO), and a packet-exchanging protocol, such as Real-time Transport Protocol (RTP), have been developed.
At present, a voice and video call service is being provided using a VoIP service between computers, a computer and an Internet Protocol (IP) terminal, and IP terminals, which can access the network based on such a protocol.
Due to the commercial launching of such VoIP services, a program capable of controlling the function of an IP terminal is installed in a computer, which is not configured to provide a VoIP service, so that the computer can be used as an auxiliary device of the IP terminal. For example, a computer can be used to control the IP terminal to originate or receive a call or to control some additional functions of the IP terminal for the sake of user convenience.
According to that conventional method, even though the computer can act as an auxiliary device to control the calling function of the IP terminal, the IP terminal is required to remain in a predetermined location since it performs the calling function. As a result, the location of the IP terminal and thus functions supported by the computer are compromised.
For example, when a VoIP service subscriber moves out of an area where the IP terminal is located, a VoIP service cannot be used. Neither may the subscriber answer an incoming call on the IP terminal or originate an outgoing call using the IP terminal. Therefore, the subscriber is subjected to an increasing burden of telephone charges.